The invention is applicable to the terahertz
optical field, and provides an electro-optic sampling device used for measuring terahertz optical pulse and a measuring method thereof. The device comprises a
polarizer, an electro-optic sampling
crystal, a
beam splitter, a first phase compensator, a second phase compensator, a first analyzer, a second analyzer and a balanced
detector. In the device, the detection light modulated by the terahertz optical pulse is divided into two paths, one of which passes through the first phase compensator and the first analyzer and is received by a first
receiver, and the other one passes through the second phase compensator and the second analyzer and is received by a second
receiver; therefore, the two beams of optical pulse introduced into the balanced
detector have the similar
noise characteristic, so as to be beneficial to eliminating
background noise. Furthermore, the first phase compensator is regulated to lead one path of light to work at the position with the best optical modulation degree, and the second phase compensator is regulated to lead the static
birefringence phase values of the two paths of light to be opposite numbers, so that the linear
working range is not affected by static
birefringence phase, and the
signal to
noise ratio can be optimized.